Magnetic membrane switch

ABSTRACT

A magnetic membrane switch includes two opposed sheets of material which are magnetized in such a way that they repel each other. At least one of these sheets is flexible. The sheets are supported so that there is a predetermined spacing between them. The opposed faces of the sheets are provided with a thin metallic pattern. Portions of the metallic pattern can be made to contact one another by pressing on localized sections of the flexible sheet. The resulting contact achieves a switching operation. By placing an alpha-numeric code on one of the sheets, the switch can be utilized as a keyboard.

Goll

[54] A MAGNETIC MEMBRANE SWITCH [72] Inventor: Frederick Martin Goll,Treichlers,

[73] Assignee: Western Electric Company, Incorporated, New York, NY.

[22] Filed: Dec. 9, 1971 [21] Appl. No.: 206,464

[52] U.S. Cl. ..335/207, 200/86 R, 200/ 159 B [51] Int. Cl. ..H0lh l/54,H01h 3/12 [58] Field of Search .200/86 R, 159 B; 335/205, 206,

[5 6] References Cited UNITED STATES PATENTS 3,383,487 5/1968 Wiener..335/205 3,617,660 11/1971 Virakinowski ..200/86 R OTHER PUBLICATIONSPin Board, IBM Technical Disclosure Bulletin,

[451 Aug. 1,1972

Vol. 8, No. 1, June 1965, page 23.

Primary Examiner-Roy N. Envall, .Ir. Attorney-W. M. Kain 5 7 1 ABSTRACTA magnetic membrane switch includes two opposed sheets of material whichare magnetized in such a way that they repel each other. At least one ofthese sheets is flexible. The sheets are supported so that there is apredetermined spacing between them. The opposed faces of the sheets areprovided with a thin metallic pattern. Portions of the metallic patterncan be made to contact one another by pressing on localized sections ofthe flexible sheet. The resulting contact achieves a switchingoperation.

By placing an alpha-numeric code on one of the sheets, the switch can beutilized as a keyboard.

1 1 Claims, 4 Drawing Figures PATENTED 11972 3 681 723 SHEET 1 0F 2BACKGROUND OF THE INVENTION 1. Field of the Invention This inventionrelates to membrane switches and their use as alpha-numeric keyboards.

2. Description of the Prior Art There is an increasing need in thetelecommunications industry for keyboard instruments of a simple andinexpensive design. A greater and greater amount of information is beingtransmitted by keyboard-type inputs. Presently utilized keyboardstypically involve individual mechanical elements for producing anelectric contact associated with each alpha-numeric symbol.

Various attempts have been made to produce a so called membrane-type ofkeyboard in which two flexible members are held in spaced relation.Electrical contact associated with a particular alpha-numeric symbol isproduced when a localized region of one of the separated membranes ismade to contact the opposed membrane. In a membrane-type keyboard, it isof course, necessary to provide some resiliency in the structure so thatthe depressed localized regions will return to a non-contact positionwhen the associated alpha-numeric symbol is released. Previous attemptsat providing the desired resiliency within membrane-type keyboards havenot been entirely successful.

SUMMARY OF THE INVENTION membrane-type keyboard.

Another object of this invention is the provision of new and usefulmethods of interconnecting conductors.

This and other objectives are achieved by providing a switch whichincludes first and second sheets of dielectric material which aremagnetized so that the opposed sheets repel one another. As least one ofthe sheets is flexible. The magnetized sheets are held in a desiredspacing such that a portion of the first sheet can be made to contact anopposed portion of the second sheet by exerting a localized force on theflexible sheet. Each of the sheets are provided with a thin metallicswitching pattern arranged so that when a particular portion of one ofthe sheets is contacted with the opposed portion, a desired switchingarrangement is achieved.

BRIEF DESCRIPTION OF THE DRAWINGS Other objects and features of thepresent invention will be more readily understood from the followingdetailed description of specific embodiments thereof, when read inconjunction with the appended drawings in which:

FIG. 1 is a perspective view of various elements mag- FIG. 4 is aschematic representation of a useful mag netic profile for the magneticelements of the keyboard of FIG. 1.

DETAILED DESCRIPTION A composite keyboard, designated generally by thenumeral 20, which embodies the inventive switching arrangement isillustrated in FIG. 1. FIG. 2 shows various elements of the keyboard 20in an expanded arrangement and with a supporting frame 21 removed. Itshould be noted that the keyboard 20 is shown with only fouralpha-numeric symbols for purposes of simplicity. The inventiveprinciples embodied in the illustrative example can be applied tokeyboards having in unlimited number of alpha-numeric symbols.

Referring now to FIG. 2, it can be seen that an upper sheet, designatedgenerally by the numeral 22, of flexible magnetic material overlies alower sheet 24 of mag netic of material. The lower sheet 24 may beeither flexible or rigid. If application of the keyboard 20 to a curvedsurface is desired, flexibility within the sheet 24 may be useful.However, if the keyboard is to be used on a flat surface, the sheet 24may be rigid.

One example of a material which is useful for making the sheets 22 and24 is a polymeric sheet available from B. F. Goodrich IndustrialProducts Company, Akron, Ohio which is sold under the productdesignation Koroseal.This material has ferrite particles embedded in apoly-vinyl chloride binder.

Each of the sheets 22 and 24 is provided with metallic elements 26thereon. The metallic elements 26 must be thin and flexible when theyare applied to flexible sheets, such as the sheet 22. One particularlyadvantageous way of applying the metallic elements to the sheets 22 and24 is by a process of vapor deposition such as evaporation, sputteringor the like.

One suitable application of the metallic elements 26 to the sheets 22and 24 was accomplished by evaporating 1,000 angstroms of titanium and50,000 anstroms of gold through metallic stainless steel masks onto thesheets 22 and 24. The metallic elements 26 were deposited on theflexible sheet 22 having a thickness of 0.050 inch. The sheet 22 wassupported 0.001 inch from the sheet 24 in an operable switchingarrangement.

In cases where a mechanically stronger conductor system is desired, itmay be advantageous to employ a metallic element formed oftitanium-palladium-coppergold.

It can be seen in FIG. 2 that the metallic elements 26 are formed withcontact portions 28 and lead portions 30. The contact portions arearranged to provide perpendicular intersections of the metallic materialwhen an alpha-numeric symbol is depressed. The lead portions 30 of eachsheet are arranged to emerge from the sheet on a substantially parallelpath so that connections to the sheets 22 and 24 can be readilyprovided.

An insulating sheet 34 is interposed between the magnetic sheets 22 and24. The insulating sheet 34 is provided with openings 36 that correspondto the position of the contact portions 28.

Referring now to FIG. 3, which is a cross-sectional view of the keyboard20, it can be seen that when a portion of the sheet 22 with one of thesymbols is depressed, electrical contact occurs between the contactportions 28 which underlie that symbol. The lead portions 30 associatedwith the particular engaged contact portions 28 are connected to theapparatus which is to be controlled by the keyboard through conventionalconnection means, such as connection terminals 40 and other connectingelements (not shown).

As illustrated in FIGS. 1-3, the upper sheet 22 is not a simple flatsheet even though a simple flat member is a perfectly acceptable andworkable configuration for the upper sheet. The upper sheet illustratedin the drawings is provided with raised portions 42 in the area of thealpha-numeric symbols. A raised portion on the outside of the keyboard,of course, facilitates ease of manual contact with the desired area ofthe keyboard. Raised portions 44 on the contact side of the sheet 22provide for more positive electrical connection between the contactportions 28. Since the sheet 22 is a polymeric substance, the raisedportions 42 and 44 can easily be molded into the sheet during thefabrication thereof. v

An alternate to the extruded or molded projection might include separatebuttons supported above the upper sheet in a loosely fitting frame (notshown).

FIG. 4 shows one workable scheme by which the sheets 22 and 24 can bemagnetized so that they will' continuously repel one another. Obviouslymany other patterns for magnetization can be utilized to accomplish thedesired object of having the alpha-numeric symbols repulsively heldabove the lower sheet 24.

Although certain embodiments of the invention have been shown in thedrawings and described in the specification, it is to be understood thatthe invention is not limited thereto, is capable of modification and canbe arranged without departing from the spirit and scope of theinvention. What is claimed is: l. A switch which comprises: a flexiblesheet of dielectric material having magnetized portions; another sheetof dielectric material opposite the first sheet having magnetizedportions, the magnetization being such that the magnetized portions ofthe opposed sheets repel one another; means for holding the sheets in adesired spaced relationship such that exerting a localized force on theflexible sheet results in a portion of the flexible sheet contacting anopposed portion of the othe sheet; and Y a conductive switching patternformed on the surfaces of each sheet which face one another, wherebyupon the exertion of the localized force a particular portion of one ofthe sheets contacts the opposed portion to effect a switching action.

2. The switch of claim 1 wherein the sheets are formed of a. polymericsubstance impregnated with magnetic particles.

3. The switch of claim 2 wherein the magnetic sheets are provided withintegral projections extending from their facing surfaces and underlyingthe metallic pattern, the ridges being positioned to provide forpositive electrical contacts when an associated area of the switch isflexed.

4. The sWitch of claim 1 wherein one of the sheets is labeled with analpha-numeric code on the side opposite that bearing the metallicpattern, whereby the switch can be utili e as a eyboard.

5. The switch 0 c aim wherein the portions of the sheet bearing thealpha-numeric symbols are raised projections.

6. The switch of claim I wherein the thin metallic pattern is formed ofcomposite, vapor-deposited layers of titanium and gold.

7. The switch of claim 6 wherein the metallic pattern includes layers ofpalladium and copper between the titanium and gold.

8. The switch of claim 1 wherein the flexible sheet has a maximumthickness of 0. inch and the spacing between the opposed surfaces of themetallic pattern is less than 0.005 inch.

9. The switch of claim I wherein an insulating sheet is interposedbetween the magnetized dielectric sheets, the insulating sheet havingopenings therein at positions which correspond to desired contact pointsof the switch.

10. A switch which comprises:

first and second opposed flexible sheets of dielectric material havingvarious portions thereof permanently magnetized, such that the opposedsheets repel one another;

means to hold the magnetized sheets in a desired spaced relationshipsuch that a portion of the first sheet can be made to contact an opposedportion of the second sheet by exerting a localized force on the firstsheet; and

a thin metallic switching pattern formed on the surfaces of each sheetwhich face one another, whereby when a particular portion of one of thesheets is contacted with the opposed portion a desired switchingarrangement is achieved.

11. A method of connecting conductors, which comprises:

magnetizing at least one magnetic portion of a first sheet of dielectricmaterial, said portion being connected to at least one conductor;

magnetizing at least one magnetic portion of a second sheet ofdielectric material, said portion being connected to at least one otherconductor, at least one of the sheets being flexible;

supporting said sheets in a spaced relationship so that said magneticportions are opposite to, spaced from, and repel each other; and

exerting a localized force on at least one sheet that is flexible toengage the conductors and thereby interconnect the conductors connectedthereto.

1. A switch which comprises: a flexible sheet of dielectric material having magnetized portions; another sheet of dielectric material opposite the first sheet having magnetized portions, the magnetization being such that the magnetized portions of the opposed sheets repel one another; means for holding the sheets in a desired spaced relationship such that exerting a localized force on the flexible sheet results in a portion of the flexible sheet contacting an opposed portion of the other sheet; and a conductive switching pattern formed on the surfaces of each sheet which face one another, whereby upon the exertion of the localized force a particular portion of one of the sheets contacts the opposed portion to effect a switching action.
 2. The switch of claim 1 wherein the sheets are formed of a polymeric substance impregnated with magnetic particles.
 3. The switch of claim 2 wherein the magnetic sheets are provided with integral projections extending from their facing surfaces and underlying the metallic pattern, the ridges being positioned to provide for positive electrical contacts when an associated area of the switch is flexed.
 4. The sWitch of claim 1 wherein one of the sheets is labeled with an alpha-numeric code on the side opposite that bearing the metallic pattern, whereby the switch can be utilized as a keyboard.
 5. The switch of claim 4 wherein the portions of the sheet bearing the alpha-numeric symbols are raised projections.
 6. The switch of claim 1 wherein the thin metallic pattern is formed of composite, vapor-deposited layers of titanium and gold.
 7. The switch of claim 6 wherein the metallic pattern includes layers of palladium and copper between the titanium and gold.
 8. The switch of claim 1 wherein the flexible sheet has a maximum thickness of 0.100 inch and the spacing between the opposed surfaces of the metallic pattern is less than 0.005 inch.
 9. The switch of claim 1 wherein an insulating sheet is interposed between the magnetized dielectric sheets, the insulating sheet having openings therein at positions which correspond to desired contact points of the switch.
 10. A switch which comprises: first and second opposed flexible sheets of dielectric material having various portions thereof permanently magnetized, such that the opposed sheets repel one another; means to hold the magnetized sheets in a desired spaced relationship such that a portion of the first sheet can be made to contact an opposed portion of the second sheet by exerting a localized force on the first sheet; and a thin metallic switching pattern formed on the surfaces of each sheet which face one another, whereby when a particular portion of one of the sheEts is contacted with the opposed portion a desired switching arrangement is achieved.
 11. A method of connecting conductors, which comprises: magnetizing at least one magnetic portion of a first sheet of dielectric material, said portion being connected to at least one conductor; magnetizing at least one magnetic portion of a second sheet of dielectric material, said portion being connected to at least one other conductor, at least one of the sheets being flexible; supporting said sheets in a spaced relationship so that said magnetic portions are opposite to, spaced from, and repel each other; and exerting a localized force on at least one sheet that is flexible to engage the conductors and thereby interconnect the conductors connected thereto. 